K 3500 Truck 4WD V8-393 6.5L DSL Turbo (1993)
1-2 Shift Solenoid Circuit
CIRCUIT DESCRIPTION
The 1-2 shift solenoid is attached to the valve body and is a normally open exhaust valve. The PCM/TCM activates the 1-2 shift solenoid by
grounding an internal quad-driver. The 1-2 shift solenoid is "ON" in 1st and 4th gears and "OFF" in 2nd and 3rd gears. When "ON," the 1-2 shift
solenoid redirects fluid to act on the shift valves. The 1-2 shift solenoid is usually gray in color.
TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks 1-2 shift solenoid and the internal transmission wiring harness for shorts.
2. This test checks for power to the shift solenoids from the ignition through the fuse.
3. This test checks CKT 1222 for a short to grounds.
4. This test checks the PCM/TCM's ability to ground or control the 1-2 shift solenoid.
DIAGNOSTIC AIDS
Check all connections at the transmission pass-thru connector. Refer to "PCM/TCM Intermittent DTC(s) or Performance."